The present invention relates generally to an apparatus for transporting passengers and, in particular, to a self-propelled elevator system.
The German patent specification No. 1 25 1 925 shows an elevator with a friction wheel drive having friction and guide wheels running in the comers of the elevator shaft. The driven friction wheels, each with separate drive motor, are positioned on the top of the elevator car diagonally opposite one another and are pressed against the running bed or track by way of a pivot support and tightening screw.
German Utility Model specification No. G 69 32 326.8 shows a "column elevator" in which a friction wheel drive provided with two pneumatic tires is attached to the elevator car. A T-shaped cross section rail or column has a base flange attached at the center of a rear side of a cross flange. The tires run on the opposite side of the cross flange and necessary contact pressure for sufficient friction is achieved by suspending the car directly from the drive and utilizing counter rollers which are mounted higher than the tires and run on the rear side of the cross flange. The contact pressure is varied by changing the connecting lever ratio and by the car weight. In the case of the latter, the car itself is used as a lever and counterweight. Therefore, the car will not always be in an exactly vertical position and during travel along the rail is prone to vibration due to the resilient pneumatic tires causing rotary oscillations about the fulcrum lying between counter roller and pneumatic tire.
The present invention is based on the task of overcoming the problems associated with the known drives by creating a friction wheel drive which is suitable for comfortable transport of persons, works mechanically independently of the car, always has sufficient friction, needs no counter rollers, needs no carrier and counterbalancing elements, makes possible a rational modular manner of construction and which is suitable not only for vertical travel, but also for horizontal travel. Furthermore, the friction between the wheels and the track surface shall be controllable for all situations.